The present invention relates to enhanced thermal protection systems for applications that demand high strength and high temperature protection such as in spacecraft, and more particularly to multi-layer thermal protection systems that utilize carbonaceous foam as the insulating material and consolidated metal matrix materials as the provider of strength.
The design of improved thermal protection systems particularly for spacecraft has been a long and demanding one. Historically, there have been two approaches in the design of such systems. Either the thermal protection system (TPS hereinafter) has offered little structural benefit and simply served to transfer loads to an underlying, primary xe2x80x9ccold structurexe2x80x9d often fabricated from, for example, a graphite-reinforced polymer material, or the structural and thermal properties of a single element system have been compromised to allow the structure to withstand elevated temperatures.
Such demands are probably no more apparent than in the requirements imposed by NASA in the development of materials systems and design approaches to support the development of integral cryogenic tank structures and thermal protection systems such as those required by reusable launch vehicles such as the X-33. These types of spacecraft experience lengthy reentry profiles and are thus exposed to high total heat input while also being exposed to relatively extreme structural demands imposed upon the xe2x80x9cairframexe2x80x9d during launch and reentry.
In the design of such vehicles, among the long list of concerns are: 1) weight; 2) cost; 3) oxidation resistance of the TPS; 4) waterproofing; and 5) structural efficiency. There are number of currently proposed systems to meet the stingent requirements in each of these areas. One such proposed system utilizes a ceramic-infiltrated woven fiber preform that offers excellent oxidation resistance and thermal protection however, at the expense of strength and weight. To improve the performance of such materials it has been proposed to use such composites as an exterior layer backed up by a primary load bearing structure. A similar, but light weight, structurally more capable and relatively lower cost solution is provided by the TPS of the present invention.
The present invention provides a multi-layer thermal protection system (TPS) comprising the combination of an oxidation resistant, high temperature capable and relatively high strength carbonaceous foam core with a high specific strength metal matrix composite layer thereon to provide a TPS that reduces the bulk and weight of currently proposed material systems. This novel TPS provides the opportunity to reduce the vehicle size and weight or increase payload capability while equaling or exceeding the performance of prior art or proposed alternative fabrication systems.